反应详情

To a mixture of 49.0 mg (0.1 mmole) of 20-(5,5-dimethyl-1,3-dioxan-2-yl)-1α,2α-epoxy-7αhydroxypregn-5-en-3β-yl acetate, 0.24 ml (3 mmoles) of pyridine and 10 ml of dry methylene chloride was added 0.1 ml (1.3 mmoles) of methyl chlorocarbonate dropwise at a temperature of 0° C. and the mixture was stirred at room temperature for 8 hours. The reaction mixture was washed with cold 1N-hydrochloric acid and the aqueous layer (washings) was extracted with methylene chloride. The extract was combined with the organic layer and the resulting mixture was washed successively with water, aqueous sodium hydrogen carbonate solution and aqueous sodium chloride solution and dried over magnesium sulfate. The solvent was then distilled off under reduced pressure and the residue was purified by silica gel chromatography (eluent: ethyl acetate-hexane=1:10, v/v) to recover 43.7 mg of 20-(5,5-dimethyl-1,3-dioxan-2-yl)-1α,2α-epoxy-7α-methoxycarbonyloxypregn-5-en-3β-yl acetate (yield: 80%).

1. washThe reaction mixture was washed with cold 1N-hydrochloric acid
2. extractionthe aqueous layer (washings) was extracted with methylene chloride
3. washthe resulting mixture was washed successively with water, aqueous sodium hydrogen carbonate solution and aqueous sodium chloride solution
4. dry with materialdried over magnesium sulfate
5. distillationThe solvent was then distilled off under reduced pressure
6. customthe residue was purified by silica gel chromatography (eluent